1. Field of the Invention
The present invention relates to an actinic ray-sensitive or radiation-sensitive resin composition for use in a process for producing a semiconductor such as an IC, a process for producing a circuit board for e.g., a thermal head or a liquid crystal, and other photofabrication processes, and relates to a method of forming a pattern with the use of the composition. More particularly, the present invention relates to an actinic ray-sensitive or radiation-sensitive resin composition that finds appropriate application when an exposure light source emits 250 nm or shorter, preferably 220 nm or shorter wavelength far ultraviolet rays, electron beams or the like, and also relates to a method of forming a pattern with the use of the composition.
In the present invention, the terms “actinic rays” and “radiation” mean, for example, a mercury lamp bright line spectrum, far ultraviolet rays represented by an excimer laser, extreme ultraviolet rays, X-rays, electron beams and the like. In the present invention, the term “light” means actinic rays or radiation.
2. Description of the Related Art
A chemical amplification photosensitive composition is a pattern forming material that is capable of, upon exposure to far ultraviolet or other radiation, generating an acid at the exposed area and, by a reaction catalyzed by the acid, changing the solubility in a developer between the area having been exposed to actinic radiation and the nonexposed area to thereby attain pattern formation on a substrate.
In the use of a KrF excimer laser as an exposure light source, a resin whose fundamental skeleton consists of a poly(hydroxystyrene) exhibiting a low absorption mainly in the region of 248 nm is employed as a major component. Accordingly, there can be attained a high sensitivity, high resolving power and favorable pattern formation. Thus, a system superior to the conventional naphthoquinone diazide/novolak resin system is realized.
On the other hand, in the use of a light source of a further shorter wavelength, for example, an ArF excimer laser (193 nm) as an exposure light source, as the compounds having an aromatic group inherently exhibit a sharp absorption in the region of 193 nm, the above-mentioned chemical amplification system has not been satisfactory.
Therefore, resists for an ArF excimer laser containing a resin with an alicyclic hydrocarbon structure have been developed. For example, the patent references (1) and (2) describe compositions containing resins each simultaneously having a polycyclic acid-decomposable repeating unit and a non-acid-decomposable repeating unit.
These resins without exception provide a chemical amplification resist having a protective group that is dissociated by an acid, thus being unstable to acids. However, in the current situation in which a further nanonization of resist pattern is demanded, it has become difficult to obtain a satisfactory resist performance by the employment of these resins only. Accordingly, ingenuity is being exercised on other components of the photoresist composition, for example, an acid generator, and study is being made on the simultaneous use of two or more types of acid generators (see, for example, the patent reference (3)).
However, the conventional resist compositions still have drawbacks. A further improvement is demanded on the Line width roughness (LWR), exposure latitude and pattern collapse performance thereof.    [Patent reference (1)] Jpn. Pat. Appln. KOKAI Publication No. (hereinafter referred to as JP-A-) 2003-167347,    [Patent reference (2)] JP-A-2003-223001, and    [Patent reference (3)] JP-A-2005-173549.